Production blade grinder



Aug. 19, 1941.

a. J. cALAM: .PRODUGTION BLADE GRINDER,

' Filed Feb. 15, 1959 a Sheets-Sheet 1 INVENTOR m 7 A L 9 A c s n N 0 wWm M GY PRODUCTION BLADE GRINDER Filed Feb. 1s, 1939 I 8-sh o ets-sheei2 -u H\ l U I INVENTOR GORDON J. CALAME F1 90 5 BY 32W 19 ATTORNEYS Aug.19, 1941.

a. J. c -LAME PRODUCTION BLADE GRINDER Filed Feb. 15, 1939 8Sheets-Sheet 4 llininh ii mvzmoa GORDON J. CALAME ATTORN EYS Aug. 19,1941. CALAME 1 2,252,879

PRODUCTION BLADE GRINDER Filed Feb. 15, 1939 8 Sheets-Sheet 5 Aug.19,1941. 6. .1. CALAME PRODUCTION BLADE GRINDER 8 Sheets-Sheet 6 FiledFeb. 15, 1939 wNN NNN NM NM Wm wmy lNVENTOR Y GORDON J. CALAME YATTORNEYS 1 G. J. GALA ME 2,252,879

PRODUCTION BLADE GRINDER Filed Feb. 15, 1959 8 Sheets-Sheet '7 /0 7 I05INVENTOR 1 1 .18 GORDON J. CALAME h BY aw r e ATTORNEYS Patented Aug.19, 1941- PRODUCTION BLADE GRINDER Gordon J. Calame, Bettendorf, IowaApplication February 15, 1939, Serial No. 256,523

37 Claims.

the grinding of each scallop or indentation and that successiveindentations be accurately spaced apart. It is, therefore, an object ofthe invention to provide an apparatus for grinding scalloped bladeswhich rigidly supports and accurately positions each blade being groundand is provided with means for taking up or compensating for slack orwear which occurs in moving parts.

The invention contemplates improvements in the means for advancing eachblade longitudinally and in intermittent fashion so that successiveportions of the cutting edge are presented to the grinding wheel andimproved means for preventing further advancement of the blade beingground after the grinding of the last scallop or indentation therein.

Another object of the invention is to provide an improved apparatus forgrinding or producing cutter blades having cutting edges in the form ofserrations or scallops, a related but more specific object of theinvention being toproduce such blades with greater accuracy anduniformity and more quickly than has previously been done.

Another object is to provide an apparatus for producing serrated orscalloped cutter blades by means of which a single grinding wheel grindsthe scallops on blades held by a plurality of fixtures which aresuccessively moved to a grinding station in proximity to the wheel sothat the periods of idle running of the grinding wheel are reduced to aminimum.

Another object is to provide an improved blade holding drum and fixturefor supporting a blade being ground and having a novelarrangement forcooling a blade during a grinding operation, the drum being formed forcirculation of cooling liquid over the major portions of both sides ofthe blade so that burning of the blade during the grinding thereof at ahigh rate of speed is avoided.

Another object is to provide an improved apparatus for operating agrinding wheel which imparts self dressing characteristics to thegrinding wheel and enables substantially continuous operation overrelatively long periods of time without refacing or dressing theabrading surface of the wheel.

A still further object of the invention is to provide an apparatus forthe production of thin, flexible blades which is simple in design andconstruction and inexpensive to manufacture and operate. Other objectsand advantages will become apparent from the following detaileddescription of a suitable embodiment of the invention which is made inconnection with the accompanying drawings, in which:

Figure 1 is a front elevational view of the blade grinding apparatus;

Fig. 2 is an end elevational view of the'blade grinding apparatus shownin Fig. 1;

Fig. 3 is a fragmentary view showing a blade which has been ground onone side by the apparatus of the present invention;

Fig. 4 is a sectional detail taken substantially on the line 44 of Fig.3 and enlarged with respect thereto; b

Fig. 5 is a fragmentary view of a blade which has been ground on bothsides by the apparatus of the present invention;

Fig. 6 is a sectional detail taken substantially on the line 6-4 of Fig.5 and enlarged with'respect thereto;

Fig. 7 is an elevational detail showing the valve tripping mechanism forcontrolling the reciprocation of the work table or carriage of theapparatus;

Fig. 8 is a sectional detail, with parts removed, taken substantially onthe line 8-4 of Fig. 7;

v Fig. 9 is a diagrammatic layout drawing showing the hydraulicmechanism and connections for actuating the carriage;

Fig,, 10 is a diagrammatic plan view of the carriage, with partsremoved, showing the ratcheting mechanisms for rotating the bladeholding fixtures in various positions;

Fig. 11 is a diagrammatic elevational view showing the carriage andvalve tripping mechanism at various positions;

Fig. 12 is a detail plan view, partly in section and with partsremoved,'taken substantially on the line I 2-12 of Fig. 19, showing oneof the blade holding fixtures and the ratcheting mechanisms associatedtherewith;

Fig. 13 is a sectional detail with parts broken away taken substantiallyon the line l3--l3 of ig. 12;

Fig. 14 is a fragmentary plan view showing the movement of theratcheting pawl;

Fig. 15 is an elevational View, partly in section and with partsremoved, showing one of the blade holding fixtures and takensubstantially on the line I--I5 of Fig. 1, being enlarged with respectthereto;

Fig. 16 is a fragmentary detail showing the engagement of the indexwheel by the indexing pawl;

Fig. 17 is a plan view. partly in section and with parts removed,showing the blade receiving drum of one of the blade holding fixtures;

Fig. 18 is an elevational view, partly in section and with partsremoved, of the apparatus shown in Fig. 17;

Fig. 19 is a vertical sectional view, with parts removed, takensubstantially on the line I9-I9 of Fig. 12, and

Fig. 20 is a diagrammatic view showing various positions of blades withrespect to the grinding wheel, and illustrating the self dressingcharacteristics of the grinding wheel and related apparatus. V

The grinding machine illustrated in the accompanying drawings includes acarriage I, reciprocally mounted on a supporting structure 2. Adjustablymounted on the carriage are left and right blade holding fixturesindicated generally by the numerals 3 and}! respectively, which arearranged to be individually reciprocated across a portion of theabrading surface of a grinding wheel 5, which is also adjustably mountedon the supporting structure 2, and driven by an electrical motor 6. Flatand V-shaped runners 9 and I0, respectively, of the carriage, ride on aflat track I and V-shaped track 8 formed across the front of thesupporting structure.

The carriage is moved back and forth over the tracks I and 8 by a rodII, secured to a depending bracket I2 formed on the right hand end ofthe carriage I, as viewed in Figs. 1 and 9.

The end of the rod II opposite the bracket 52 carries a double actingpiston i3 which. slides within a cylinder I4. The ends of the cylinderI4 are closed and are connected to a carriage reciprocating controlvalve I5 by means of conduits I6 and I1, which communicate with the leftand right hand ends respectively of the cylinder, as viewed in Figs. 1and 9. High pressure fluid is supplied to the Valve I5 from a reservoirby means of a pump 2! through conduit 22. A throttling valve 23 isinterposed in the conduit 22 so as to regulate the pressure at whichfluid is supplied to the valve I51. The carriage control valve I5 isactuated through a rod 24 by means of a pivoted lever 25; the lattercarrying on its upper end an element 26 which is engaged by dependingfingers of valve actuating dogs, to be later described, mounted on thecarriage I. v

The actuating mechanism for the carriage is arranged so that while theblade holding fixture 3 is disposed at the grinding station adjacent thegrinding wheel 5, the carriage I is reciprocated over a relatively shortpath C, Figs. 10 and 1'7, under the control of valve shifting dogs I 8and I9. Similarly, when the blade holding. fixture 4 is adjacent thegrinding wheel, the carriage is reciprocated over a relatively shortpath under the control of valve shifting dogs 21 and 28..

When the carriage I is being moved to the left, as viewed in Fig-s. 1and 9, the pivoted arm 25 is substantially in the position shownv inFig. 9 and the rod 24 is withdrawn from the valve 15 so as to admit highpressure fluid to the right hand end of the cylinder I 3 through theconduit I1. During movementofv the carriage to the right as viewed inthe same figures, the pivot arm 25 is tilted in a counter-clockwisedirection from that shown in Fig. 9, so that the rod 24 moves into thevalve I5 and high pressure'fiuid is admitted to the left hand end of thecylinder I 4 through the conduit I6, as .viewed in Fig. 9. The valve I5is arranged so that when high pressure fiuid is being introduced intothe cylinder I4 through the conduit I6, fiuid from the right hand end ofthe cylinder fiows through the conduit I! to the valve I5 and isdischarged through a return conduit 29 which conducts the fluid to thereservoir 20. Similarly, when high pressure fluid is introduced into theright hand end of the cylinder through the conduit II, fluid from theleft hand end of the cylinder I l flows through conduit I6 to the valveI5 and is discharged into the reservoir through the conduit 29.

As shown in Fig. 8, the arm 25 is pivoted at 30 on the inside of frontpanel 3I of the supporting structure 2. An angular portion 32 at the topof the arm 25 extends through an elongated slot 33 formed in the panel3| and carries on the outside of the supporting structure the element26. This element has offset stops 34 and 35 which are engaged by fingersof the valve actuating dogs. The dogs I8 and 21 have depending therefromfingers 31 and 39 respectively which are in alignment with one anotherand with the stop 35 of the valve shifting element to move the latter tothe right as viewed in Figs.

l. 7 and 9. The dogs I9 and 28 have depending vtherefromfingers 36 and38 respectively which are in alignment with one another and with thestop 34 to engage the latter and shift the element 26 to the left asviewed in Figs. 1, '7 and 9.

The operation of the reciprocating carriage under the control of dogs I8and I9 is readily understood from Fig. '7. Assuming the carriage ismoving to the right as viewed in Figs. 1, 7 and 9, finger 31 of the dogI8 engages the stop 35 of the valve shifting element after apredetermined travel of the carriage I, and shifts the element 26 tosubstantially the full line position indicated in Fig. 7. This movementof the element 26 shifts the arm 25 to substantially the positionindicated in Fig. 9, so as to actuate the valve I5 to admit highpressure fluid to the right hand end of the cylinder I l through theconduit I1, thus energizing the carriage in a reverse direction. Thisreverse energization of the carriage through the hydraulic cylinder I lfirst stops the movement of the carriage to the right and then actuatesthe carriage for movement to the left. After a predetermined traveltowards the left, as viewed in Figs. 1, 7 and 9, the finger 36 of thedog I9 engages the stop 3t of the valve shifting element-and moves it towards the right, equal to the previous travel in the same direction, thefinger 3'! of the valve actuating dog I8 again engages the stop 35 toshift the valve actuating element 26 and the cycle is repeated. In thismanner the dogs I8 and I9 control the reciprocation of the carriage overthe path C While the bladeholding fixture 3 is at the grinding stationadjacent the grinding wheel 5. Similarly, the dogs 21 and 28 control thereciprocation of the carriage while the blade holding fixture 4 is atthe grinding station adjacent the grinding wheel 5.

A way 42 is formed along the front side of the carriage I to receive thedogs I8, I9, 2Tand This way has formed therein a T slot 43 whichreceives bolts- 44 to secure the dogs in place. Accordingly, the dogsmay be individually adjusted longitudinally with respect to the carriageso as to accurately determine the lengths and relative locations of theseveral paths of reciprocation of the carriage. Thus the pair of dogs I8and I9 may be moved further apart than shown so as to increase thelengthpf the path C over which the carriage rcciprocates while the bladeholding fixture 3 is adjacent the grinding wheel. Similarly, the dogs2'! and 28 may be shifted further apart so as to lengthen the path overwhich the carriage reciprocates while theblade holding fixture 4 isadjacent the grind ing wheel.

The finger 36 ofthe dog I9 and the finger 39. of the dg2'I are pivotallymounted on spindles 45 and provided witlr. upstanding arms 46. When thecarriage is being reciprocated under the control of the dogs I8 and I9with the blade holding fixture 3 adjacent the grinding wheel, theoperator, by moving the arm 46 to substantially the position indicatedby the broken lines of Figg'l, can pivot the finger 36 in acounter-clockwise direction and withdraw it so as to avoid contact withthe stop 34 of the valve shitting element 26. The valve I thus continuesto supply fluid under pressure to the cylinder I4 after the carriagereaches its normal limit of movement for reciprocation over the path Cwith the fixture .3 at the grinding station, so that the carriagecontinues to move to the left to remove the blade holding fixture 3 awayfrom the grinding wheel and advance the blade holding fixture 4 to thegrinding station adjacent the grinding Wheel.

The carriage continues to advance to the left until the finger 38 of thedog 28 engages the stop 34 and shifts the element 26 to the left toreverse the valve I5, as previously described. Similarly, by means ofthe upstanding arm 46 on the finger 39, the latter may be withdrawn soas to avoid contact with the stop 35, and shift the carriage to theright beyond the normal limit of movement for reciprocation of thefixture 4 at the grinding station, thus moving fixture 4' away from thegrinding wheel and advancing the blade holding fixture 3 to a positionadjacent the grinding wheel.

After a blade has been ground on the fixture 4, for example, and thefixture moved away from the grinding station, the operator removes theground blade from the fixture and replaces it with a fresh blade to beground while another blade previously mounted on the fixture 3 is beingcarried back and forth across the abrading surface of the grinding wheel5. After the grinding of the blade on the fixture 3 is completed, theoperator, by moving thearm 46 and withdrawing the finger 36 so as tomiss the stop 34, effects a shifting of the carriage so as to bring theblade holding fixture 4 with the fresh blade to be ground thereon, intooperative position with respect to the grindingwheel 5. This samemovement of the carriage withdraws the blade holding fixture 3 from thegrinding'wheel so that the operator can remove the ground bladetherefrom and either reverse the blade so as to grind the opposite sidethereof or replace it with a fresh, ungrouncl blade.

Since no grinding is being done while one blade fixture is withdrawnfrom adjacent the grinding wheel and another is brought into grindingposition, it is desirable that the rate of travel or speed of thecarriage be increased so as to save time. For this purpose a by-passconduit 49 is connected in parallel with the conduit 22 around thethrottle valve 23. The flow of fluid through the conduit 49 iscontrolled by means of a quick acting valve 50 actuated by upwardlyextending A member 52 (Fig. 8) is secured on the upper end of the rod 5Iand carries a roller 53 which is engaged by a rapid traverse track orcam 54 depending from the way 42 between I The the dogs I9 and 21, asshown in Fig. '7. member 52 is centrally apertured and straddles theangular portion 32 of the pivot arm 25 so that the roller 53 is normallydisposed between the valve shifting element 26 and the front panel 3I ofthe supporting structure 32 about midway between the stops 34 and 35.The ends of the cam 54 are rounded as indicated at 55. to effect arelatively smooth or gradual depression of the rod5I which actuates thevalve 53. The relatively large quantity of high pressure fluid admittedthrough the conduit 49 to the valve I5 accelerates the velocity of thecarriage I while one blade holding fixture is being withdrawn fromoperative position adjacent the grinding wheel and the other bladeholding fixture is being advanced to the grinding wheel.

Desirably, a main control valve 56 is arranged to shut off the supply offluid from the pump to the carriage control valve I5 and is actuated bya lever 51 mounted on the front panel 3I of the supporting structure.The rod 5| is guided by brackets 60 .with which it has slidingengagevarious elements included in the fixture 3 are not identical withtheir counterparts in the fixture 4 but may be termed left handed partsY while the similar elements of fixture 4 may be termed right handedparts.

Each of the blade holding fixtures comprises a pedestal membersupported-on bed 66 of the carriage I and adjustably secured thereto bybolts 61 (Fig. 15) anchored in T-slots 68. A

base 69 has a sliding dovetail connection 10 (Fig.

19) with the top of the pedestal 65 for hori zontal adjustment thereof,transversely with respect to the direction of reciprocation of thecarriage I. This transverse adjustment is effected by means of athreaded rod II journaled at 1?. (Fig. 15) at the front end of thepedestal 65 and extending longitudinally. through a" trench 73 formed inthe pedestal. A block I4 is secured to the underside of the base 69 andthreadedly receives the rod IL. Endwise movement of the rod 'II withrespect to the pedestal 85 is prevented by an annular collar I5 formedvon the rod 'II which engages one end of the journal I2 and an annularbearing Washer 16 secured against the opposite end of the journal I2 byjamb nuts 11. The rod 1|, beyond operator's side 18 of the carriage I issquared as indicated at 19 to receive a suitable tool for turning therod when adjusting the base 69 transversely with respect to the pedestaland carriage. De'sirably, graduations 80 are formed on the collar I5 tofacilitate the accurate determination of the amount of the adjustmentmade in the base 69.

An upstanding bracket 8| is formed at the operators end of the base 89and is provided with a substantially vertical bearing surface 82, Fig.12, against which is adjustably secured a footing member 83 of bodyportion 84.

The body of the blade holding fixture is thus disposed above the base 89and pedestal 65 and is supported cantilever fashion by the bracket 8| ofthe base. The footing 83 is slidable on the bearing surface 82 of thebracket 8| and a vertically disposed key 85 secured by screws 86 in agroove formed in the bracket, has sliding engagement in a groove formedin the bearing surface 82 to guide the body portion 84 and maintain thelatter in proper alignment with the base and pedestal. An adjusting bolt81, journaled in boss 88 formed on the bracket 8|, has threadedengagement with a laterally extending block 89 screwed into the bodyportion 84 and extends through a vertically elongated I slot 90 formedin the lower portion of the bracket 8|. The body 84 of the blade holdingfixture may be adjusted vertically by rotating the bolt 81, so as toelevate or lower the body portion with respect to the base and pedestalof the blade holding fixture and the bed 66 of the carriage I. In orderto tightly secure the body to the base 89, a pair of cap screws 9|,having their heads bearing against the bracket 8|, pass throughvertically elongated slots 92 (Fig. 1) in the bracket 8| and arethreadedly secured in'the footing 83 of the body 84. The end of the bodyportion 88 opposite the footing 83 is supported by a stud 93 whichextends upwardly from the base 89 and passes through a boss 94 formed onthe body portion 84 of the blade holding fixture. A; nut 95 above andbelow the boss 94 lock the latter to the stud 93.

Desirably, agib 96 (Fig. 19) is interposed between the pedestal 65 andbase 88 in. a dovetail connection 10. This gib is laterally engaged byrods 91 threadedly received in the base 89 and arranged to bear againstthe gib when tightened by means of thumb wheels 98 secured on the outerends of the rods. In this manner the base 09 can be locked in adjustedposition with respect to the pedestal 65.

The body portion 84 has a central vertically extending bore IOI (Fig.l9) which receives a rotatable spindle I02. The spindle is journaled intop and bottom tapered roller bearing assemblies I03 and I04respectively. The outer race of the bottom..roller bearing seats in acounterbore I of the bore IM and the inner race thereof embraces thespindle I02.and seats against a circumferential collar I06 formedthereon adjacent the lower end of the spindle. The outer race of theupper roller bearing I 03 seats in a counterbore I01 at the upper end ofthe bore I 0| and the inner race of the bearing is adjust- I I ably heldby a pair of lock" nuts I08. Thus by 1 means of the adjustable lock nutsand the collar I06 the inner races of the top and bottom roller bearingscan be drawn together so as to tighten the journals and prevent lateralplay or movement of the spindle I02 in the body 84 of the blade holdingfixture. This feature is of considerable importance since it isessential that the blade be rigidly held during the grindingthereof sothat the scallops formed along the cutting edge of the blade are uniformand evenly spaced.

A reduced diameter portion I09 at the upper end of the spindle I 02receives a blade holding drum or head I I0, to be later described, whichis supported on a shoulder III formed at the bottom of the reduceddiameter portion I09 of the spindle. A star wheel II2 surmounts thespindle I 02 and is threadedly secured thereto, bearing against an upperportion of the head IIO to secure the latter against rotation on there-' duced diameter portion I09. A number of shims II5 may be disposedbetween the head I I0 and circumferential shoulder III of the spindleI02 so as to provide fine, accurate vertical adjustment of the head H0.The star wheel II2 prevents rotation of the blade holding drum on thespindle and affords a ready means by which the operator can rotate thedrum and spindle in loading the drums with a blade to be ground.

A trough II6 surmounts the body 88 of the blade holding fixture and hasa bottom portion II! which slopes downwardly and away from v the bladeholding head H0. The central por tion of the trough rests upon and issecured to the body 84 and is provided with an upwardly directedcircular flange IE8 which is received in an annular channel or grooveIIS formed in the bottom of the head H0, see Fig. 18. The flange H8 andchannel 9 serve as a trap to prevent grinding fluid used in the grindingof the blade from flowing underneath the head H0 into the bearings I03and I04 and other moving parts of the blade holding fixture; The troughIII; has upwardly extending end walls I20 and a side wall I2I. The sideof the trough disposed adjacent the grinding wheel 5 and opposite theside wall I2I is open, as shown in Fig. 15, to permit the readydischarge of grinding fluid therefrom.

A pair of spaced parallel peripheral abutments I22 and I23 are formedcircumferentially about the outer margin of the drum H0 and inconcentric relation with respect to the axis of the spindle I 02. Theseabutments serve as a backing for a relatively thin flexible blade 924,which, during the grinding of the latter, is bent or deformed into anarcuate shape around the drum '0. An upwardly directed circumferentialshoulder I25 is formed on the blade holding drum IIB adjacent the bottomabutment I28 to support the bottom or non-cutting edge of the blade I28during the grinding of top or cutting edge I28 of the latter. The topabutment I22 is arranged to engage the concave side of the blade I24below the blade edge I28 which is to be abraded by the grinding wheel 5and at a region of the blade spaced from the region engaged by theabutment I23. In this manner the top abutment I22 avoids contact withthe grinding wheel while serving as a reinforcement for the blade in thegrinding area.

As shown in Fig. 18, the top abutment I22 is formed on a radiallyextending fin or flange I2'i and a circumferential channel or groove I28is disposed between the top and bottom abutments I22 and I23. Thischannel is normally covered by the blade I24 when the latter is inposition for grinding and a plurality of apertures I29 are formed in theflange I21 so as to admit grinding or cooling fluid to the channel I28during the grinding operation. The cooling liquid thus admitted to thechannely remains in contact with the concave side of the blade I24 tocool the latter.

Adjacent the flange I21 and on the top surface of the drum or head H isformed an upwardly directed circumferential flange I30 which extendsabove the level of the top edge I26 of the blade I24 and serves todirect cooling liquid into the apertures I29.

A central annular channel I33 isformed in the topof the drum IIO aboutthe portion of the latter which is engaged by the downwardly directedshoulder of the star wheel II2. channel connects witha segmentalcut-away portion I34 (Fig. 1'7) which extends through the periphery ofthe head. A pair of blade holding arms I35 and I36 are disposed in thecut-away portion I34 and extend radially from rings I31 and I38respectively, which ride in the channel I33 about the central portion ofthe head, being retained therein by the star wheel I I2. The arms I35and I36 are of such a length that their ends I39Iand I40 respectivelydescribe arcs of sumstantially equal radius with the abutments I22 andI23 and are provided with removable blade holding pins MI and I42respectively. These pins are received in drill holes in the arms andsecured by set screws I43 which permit adjustment or replacement of thepins as desired. A laterally extending flange I44 formed on the arm I35is disposed against the horizontal bottom I45 of the cut-away portionI34 and is provided with an arcuate slot I46 concentric with the axis ofthe spindle I02. A tightening screw I41 extends through the slot I46and,is threaded into the head IIO to retain the arm I35 in adjustedposition. A helical compression spring I48 has its ends seated insockets formed in radial side walls I49 of the cut-away portion I34 andone side of the arm I36 to urge the arm toward a stop pin I50 secured inthe floor I45 of the cut-away portion and maintain a suitable tension onthe blade being ground. I

Inorder to grind a scallop or serration in the edge I26 of the bladevI124, the head IIO must be secured against rotation as the carriage andfixture carry the blade across the peripheral abrading surface of thegrinding wheel. A succession of scallops or serrations are ground in theblade by rotating the head or drum I I0 a predetermined amount aftereach grinding operation. This control. of the blade holding head iseffected by means of an index wheel I53 (Fig. 19) received on a reduceddiameter portion I54 of the spindle I02 at the lower end of the latter.'

The index wheel abuts against the, collar .106

and is secured in place by a plurality of axially extending screws oneof which is indicated at I55. These screws have their heads recessed inthe wheel I53 and are threadedly engaged in apertures formedin thecollar I06. A multiplicity of equally spaced teeth I56 are formed aboutthe therefrom in a radial direction with respect to 75 by the ratchetingpawl I04, a circumferential This the spindle I02 is a housing I59 (Fig.19) which has slidably mounted for reciprocation therein an indexingpawl I60. This pawl is movable toward and away from the toothedperiphery of the index wheel I53 and is provided with a wedgeshaped noseI6I (Fig- 16) engageable between adjacent teeth of the wheel I53 of thenose I6I is parallel to the line of reciprocation of the pawl I60 and isthus substantially parallel with the radial faces I51 of the teeth I56so as to bear flatwise thereagalnst. Face I63 on the opposite side ofthe nose I6I from the face I62 is disposed at an angle with respect tothe direction of reciprocation of the pawl I60 and is engageable withthe angularly disposed faces I58 of the ratchet teeth I56. Helicalcompression spring I64, set in a longitudinal bore I65 formed in thebody of the pawl, normally urges the pawl I60 to the left as viewed inFigs. 12 and 16 so that the inclined face I63 on the nose I6I has awedging action with the inclined face I58 of one of the ratchet teethI56 to hold the radial face I62 of the pawl nose I6I against the radialface I51 of the next adjacent tooth of the indexing wheel. The springI64 seats against a conical end 'formed on an adjusting screw I66threadedly received in a removable cap I61 at the end of the housingI59. A tapered gib I68 is disposed between oneside of the pawl I60 andthe adjacent wall of the housing I59 to prevent lateral shifting of thepawl. One end of this gib extends throughfthe cap I61 and is providedwith a notch I69 which receives a peripheral por- 1 tion of a. knurledadjusting wheel I10, carried on A pin I12 having a press fit in a drillhole in the pawl I60 extends through an elongated slotted opening I13formed in the under side of the housing I59 and is received in asocketof a lever I14 carried by a stud I15 (Fig. 15) pivot ally mounted in aboss I16 formed on the housing 5 I I59. By pivotingthe lever I14away'from the fixture in a counter-clockwise direction, as

viewed in Fig. 12, the pawl I60 may be withdrawn I from the indexingwheel I53 so that the operator can rotate the blade carrying head ordrum IIO by means of the star wheel II2.

A ring member I19 is mounted for oscillatory rotative movement on acylindrical portion I (Fig. 19) formed at the lower end of the body Thetop surface of the ring member I19 abuts against a circumferentialshoulder I8I of the body and the ring member is retained on thecylindrical portion I80 by means of a removable flange member I82,attached to the lower end of the body 84 by means of a plurality ofscrews, one of which is indicated at I83.

A pawl I04, pivoted to an arm I86 of the ring member I19, is pressed bymeans of a coil spring I81 against the toothed periphery of the indexwheel I53. Upon each movement of the ring member I19 in acounter-clockwise direction, as

viewed in Fig. 12, the pawl I84 rotates the index wheel I53 and spindleI02. Thus the blade drum or head "IIO'of the fixture 4 1s rotated in acounter-clockwise direction as viewed from above, 0 and in acorresponding manner the blade holding drum of the fixture 3, shown inFig. 17, is rotated in a clockwise direction as indicated by the arrow.In order to Withdraw the indexing pawl I60 from between adjacent teethof the index wheel I53 during the rotation of the latter Qne face I62blade holding head. 0, by the ratcheting pawl I84, continued oscillationof the ring member I19 is ineffective to further rotate the partsmentioned. For this purpose a tooth blanking ele-- ment I90 (Figs. 13and 14) is secured to a disk I9I adjustably carried on the end of thereduced diameter bottom portion I54 of the spindle I02.

As shown in Fig. 19, the disk I9I underlies the index wheel I53 and issecured against rotation on the spindle by means of a radially disposedset 1 screw I92. A circular cap I93, secured on the end of the spindleI02, retains the disk I! in place when the set screw I92 is released.-The tooth blank I90 extends upwardly from the periphery of the disk I9I(which is of but slightly greater diameter than the indexing wheel I53)-and is disposed in overlying relation with respect to a number of theteeth I56.

Accordingly, as the spindle I02 and related parts .are rotated by theratcheting pawl I84, the tooth blank I90 approaches the pawl and finallyunderlies the same, as shown in Fig. 14, at a predetermined position ofthe blade holding drum or head IIO with respect to the grinding wheel sothat further reciprocation of the pawl I84 is ineffective to rotate theindexing wheel I53, the pawl mere- 1y sliding over the outer surface ofthe tooth blank I90.

The pawls and the cam carrying ring members 119 of the blade holdingfixtures 3 and 4 are actuated by reciprocating rods I 96 (Fig. 12) whichare mounted for longitudinal sliding movement in the apertured end ofbrackets I91 and I98 extending laterally from the pedestals 65. FittingsI99, longitudinally adjustable on the reciprocable rods I96 by means ofadjusting screws 200 seating in longitudinal grooves I of the rods, haveelongated openings 202 in their upper sides which receive depending pins203 (Fig. 19) secured in the arms I86 of the respective ring membersI19.

A helical compression spring 204 is disposed about each of thereciprocating rods I96 at the operator's end thereof to normally urgethe rods in a direction away from the operator. One end of each of thesprings 204 rests against the rod receiving portion of the bracket I91and the opposite end of each of the springs abuts against an adjustablecollar 205 threadedly received on a threaded portion 206 of the rod I96and secured in adjusted position by a set screw 201. Collars 208 on theends of the rods I96 limit the movements of the latter by engagementwith the outside of the rod receiving portions of the brackets I91 andI98.

Reciprocation of each of the rods I96 is effected through the pair ofarms 209 and 2I0 carried by a pivot stud 2| I journalled in a b-racket2I2 formed on the rear side of the pedestal. The free end of each of thearms 209 is formed with a yoke 2I3 which straddles flattened portion 2of the rod I96, thus preventing rotation of the rod in the brackets I91and I98; elongated slots 2I5 formed in the yokes receive pins 2I6secured in the rods I96.

An annular collar 2I9 is formed on the stud 2H and rests on the top ofthe boss 2I2. By means of a tightening nut 220 and a lock washer 22I,the arm 209 is forced against the collar 2I9' so as to prevent rotationof the arm relative to the stud 2! I. The portion of the stud whichprojects from the bottom of the boss 2I2 rotatably receives the 'arm,2I0, which is retained thereon by a lever 222 (Fig. l5) secured againstrotation on the stud by a taper pin'223. An upwardly projecting pin 224'formedon the lever 222 is engag-eable with a finger 225 formed on thearm 2I0. A helical compression spring 226 seated in sockets formed onthe arm 2I0 and lever 222 normally retains the finger 225 in engagementwith the pin 224 as shown in Fig. 12. As the carriage I is reciprocatedon the supporting structure 2 with one of the blade holding fixtures atthegrinding station adjacent the grinding wheel 5, a roller 221 on theend of the arm 2I0 engages a V-shaped cam member 228 secured to thesupporting structure substantially in the plane of rotation of thegrinding wheel.

As each of the blade holding fixtures is advanced into operatingposition adjacent the grinding wheel 5 the roller'221 associatedtherewith rides up one face and over crest 229 of the cam member 228.For example, blade holding fixture 4 is shown in Fig. 12 with thespindle 'I02 substantially on the center line of the grinding wheel, andin reaching this position it moves from right to left relative to thecam member 228, the roller 221 first engaging and riding up compressed.

Upon movement of the carriage I to the right, as viewed in Figs. 1, 10,12, and 19, the roller 221 engages the inclined face 23I of the cammember 228 so that the arm 2I0 is pivoted on the stud 2H, and the finger225 engages the pin 224 so that the lever 222 and arm 209, which moveasa unit, are likewise pivoted to move the rod I96 toward the operator,causing a'rotative movement of the ring member I19 about the body. 84 ofthe blade holding fixture. This movement of the ring member withdrawsthe indexing pawl I60 by means of the cam surface I88, as previouslydescribed, and effects a rotation of the'spindle I02, and blade holdingdrum IIO of a predetermined amount, by means of the ratcheting pawl I84.As the blade holding fixture is I moved away from the grinding stationthe roller '221 on the arm 2I0 again rides over the crest 229 of the cammember 228 causing a longitudinal movement of the rod I96 against thecompression of the spring 204.

The grinding wheel or abrader 5 and the actuating motor 6 are mounted ona table, 234 slidably carried on the. supporting structure 2 by means ofa dovetailconnection 235 (Fig. 1)

for movement toward and away from the ear riage I, as desired. Thismovement is effected by means of a threaded shaft 236, (Fig. 2)

mounted for rotation in the supporting struc ture 2 and threadedlyreceived in the end of a member 231 depending from the table234. Theshaft 236 is secured against endwise movement in the supportingstructure and one end there- .of which projects through the front panel3| of.the supporting structure has secured thereon Y a crank wheel 238by means of which the operator can effect rotation of the shaft foradjustment of the position of the table 234. A clamping block 239 iscarried by a threaded rod 240 I rotatably mounted in the table 234, and,upon being drawnupwardly against shoulders 2 formed on the supportingstructure, locks the table 234 in adjusted position. A collar 242 on therod 240 prevents vertical or longitudinal movement of the latterrelative to the table 234 i and the rod is provided with a squared end243 for receiving a suitable turning tool. the

grinding wheel 5 becomes worn, the adjusting handwheel 238 can be usedto advance the wheel toward the table I so as to be in correct positionat the grinding station relative to the blade holding drumsIIO on thefixtures 3 and 4. A

corresponding adjustment is available, as previously described,by meansof the rod H which moves the base of the fixtures relative to thecarriage.

A driving connection between the motor; and the grinding wheel 5 iseffected by means of a belt 244 and the grinding wheel is arranged torotate on an axis substantially parallel' to the direction ofreciprocation of the car- "riage I so that during a grinding operation aand reservoir (not shown) carried by the supporting structure, isarranged to direct a stream of the liquid onto the bl de being groundand the periphery of the grinding wheel 5, the latter being rotated inthe irection of the arrow in Fig. 2. This cooling liquid fiows over theouter surface of'the work being ground, and by means of the upstandingflange I30, the cooling liquid is directed to flow through the upwardlyopening apertures I29 and into the channel I28 where the cooling liquidcontacts the inner side of the blade being ground. As shown in Fig. '18,the abutments I22 and I23 are relatively narrow and contact but a minorportionofthe rear or inside surface of the blade being ground, leavingthe major portion of the blade surface exposed to the cooling liquid.Furthermore, the abutment I22 is disposed closely adjacent the edge ofthe blade being ground to support the same and resist deflectionthereof.

,In this manner the major portion of the inside surface and all of theoutside surface of the relatively thin flexible blade are substan tiallysubmerged in the cooling'liquid during the grinding operation so thatthe generated heat is quickly and effectively carried off by thecirculating coolant, and burning of the relatively thin metal blade isavoided. Referring to the diagram shown in Fig. 10,

the movement of the carriage I during operation of the machine. will bedescribed by indieating the various positions taken by the rods I96which actuate the ratcheting pawls I84. In

this figure various parts previously described and associated with theblade holding fixture 3 are identified by suffixing the numeral -3 rod I96-4 takes the 25 250 and 252.

the identifying numeral for the part. Similarly, the parts associatedwith the blade holding fix- I ture 4 are indicated by the numeral 4suffixed to the part identifying number.

When the carriage I is at its extreme limit of movement to the right(substantially in the position indicated by the full lines of Fig. l),the rods I96-3 and I96-4 of the blade holding fixtures 3 and 4respectivelinare at 252 and 10 253 respectively, indicated by the solidlines of Fig. 10, the spindle I02 of the blade holding fixture 3 havingmovedbeyond centerline 241 of the grinding wheel 5 a distance equal toabout one-half the length of a scallop or 5 serration. Upon movement ofthe carriage to its extreme limit of movement to theleft (indicated bythe broken lines of Fig. 1) the rod I96-3 (Fig. 10) of the blade holdingfixture 3 takes the position indicated by line 250 and the positionindicated 25I. Thus the movement of the rod I96--4 is indicated by thedistance A between lines 25I and 253, while the movement of the rod I93-3 isindicated by the distance B, between lines The distances A and Bare, of course, equal to one another and controlled by the distancebetween the dogs I8 and 28.

. Whilethe blade holding fixture 3 is at the operating or grindingstation the carriage I is reciprocated over a path, the limits of whichare indicated by the line 252, previously mentioned, and a line 254which is removed from the line 252 at a distance C toward the line 250.The ,distance C, which represents the length of the work and ratchetingstrokes of the carriage and fixtures is controlled by the dogs I8 and I9for the fixture 3, and by the dogs 21 and 28 for the fixture 4. Usuallythe distance C is the same for both fixtures, and accordingly, while thedescription of the movements of fixtures at the grinding station is madewith specific reference to fixture 3, it is to be understood that themovements .of the fixture 4 are similar, but take place in reversedirections on the opposite side of the 5 grinding wheel from themovements of the fixture 3.

As shown in Fig. 17, C designates the distance from thelocation of thecenterline of the fixture 3 when the latter is at the end of a grindingor work stroke, indicated at 255, to the location of the centerline ofthe fixture 3 when the latter is at the end of a ratcheting stroke,indicated at 256. These positions of the fixture centerline correspondto the positions 252 and 254, respectively, of the rod I963 (Fig.

10). When the drum III) of the fixture 3 is in the position shown inFig. 17, with respect v to the grinding wheel 5, the rod I96-3 is in theposition indicated by the line 252 (Fig. 10). As

the spindle and blade holding drum centerline moves from 256 to 255(Fig. 17) the blade carrying head or drum H0 is carried over a workstroke during which the cutting of a serration or scallop in the bladeI24 takes place. After each work or,grinding stroke, ,/and while thespindle centerline is moving from 255 to 258, the spindle I02 is rotatedby engagement of the roller 221-3 with the face 230iof the cam member228, an amount sufficient to bring the next after 75 ing stroke, thecenterline of the'spindle or blade by line adjacent portion of the bladebeing ground into into arcuate shape.

holding fixture moves a material distance away from the line 255 beforeany rotation of the spindle occurs. For example, by suitable adjustmentof the parts the spindle centerline may reach a position such asindicated by line 251 (Fig. 17) before the cam roller 221-3 engages thecam surface 230 and starts the ratcheting of the spindle. In this mannerrotation of the blade carrying drum I10 while the blade is in contactwith the grinding wheel 5 is avoided. Accordingly, on the return orratcheting stroke the spindle travels a distance D before any ratchetingoccurs and the entire ratcheting or rotational movement of the drum IIOoccurs while the spindle or blade holding fixture centerline moves adistance E.

In order to produce a series of scallops or serrations on a blade, thelatter is mounted on one of the blade holding drums I so that theportion drawn across the peripheral abrading surface of the grindingwheel 5 is bowed or bent The body 84 of the blade holding fixture isadjusted vertically so that the blade is supported with the top orcutting edge I26 thereof disposed in a horizontal plane materially belowthe horizontal center line of the grinding wheel 5, which is indicatedby the numeral 258 (Fig, 1 8). In this manner the por- ,tion of theabrading surface of the rotating grinding wheel which contacts the bladeis disposed, because of the peripheral curvature of the wheel, at anangle to the plane of the blade, which corresponds to the desired bevelon the finished blade.

During the operation of a machine of the character described above forthe commercial manufacture of blades having scalloped edges, such for.example as relatively thin flexible blades for reciprocating breadslicing machines, the operator sets the motor 6 in operation to drivethe grinding wheel 5 at a relatively high peripheral speed and startsthe pump 2| to supply high pressure fluid for actuating the piston I3 inthe hydraulic cylinder I4. The carriage I is moved to the left as viewedin Fig. 1, to-substantially the dotted line position shown and a thinflexible blade blank is fixed to the blade holding drum IIO of the bladeholding fixture 3. As shown in Fig. 17, the blade blank is shorter thanthe circumference of the drum I 10 but of greater length than theabutments I22 and I23 so that the ends of the blade blank project beyondthe ends of the abutment across portions of the cut-away portion I34.Holes 259 are formed in the blade blanks adjacent the ends thereof andare received on the pins MI and I42 to secure the blade to the drum IIO.A partially ground blade or blade blank is secured on the drum byplacing one of the holes 259 over the pin I4I on the arm I35 and bowingand drawing the blade around the abutments I22 and I23 so that the rearor bottom edge thereof seats against the circumferential shoulder I25 ofthe drum. The operator then pivots the arm I36, compressing the springI48, and locates the pin I42 in the hole 259 at the opposite end of theblade blank. In this manner the blade is tensioned and held in bent formtightly against the shoulders or abutments I22 and I23 by the force ofthe spring I48.

The distance from one end of the blade blank I 24 or the hole 259 whichis received on the pin I4I to the first scallop or serration isdetermined by the position in which the operator sets the head I10before starting the grinding operation.

approximately in the position desired. Final ad-' justment of theposition of the blade blank about the drum is effected by means of theelongated slot I46 and screw I41 which permit variation of the positionof the arm I35. Upon thus determining where the center of the firstscallop in the blade blank will be ground, the operator can make atemporary gauge mark 260 on the head of the drum which indicates theportion of the drum which is to be turned toward the grind ing wheel atthe beginning of each grinding operation so as to properly locate thefirst scallop. Each time the operator sets the fixture to grind a freshblade blank or to grind the reverse side of a previously ground bladeblank, he rotates the drum IIO after releasing the indexing pawl.

I60 by means of the hand lever I14 to dispose the gauge mark 260parallel to the plane of ro I 'I' tation of the grinding wheel.

Upon opening the main control valve 56, the hydraulic cylinder I4 movesto the right, as

viewed in Fig. 1, so that the blade holding fixture 3 with the ungroundblade blank in place is advanced to the grinding station adjacent thegrinding wheel 3, and across the face of the wheel, substantially to thefull line position shown in that figure. The limit of movement iscontrolled by the finger 31 of the dog I8 which actuates the valve 15through thevalve shifting element 26 to reverse the hydraulic cylindermechanism and move the carriage to the left.

During the movement of the carriage to the right the drum H0 is heldrigidly against rotation by means of the indexing pawl I60. During themovement to the left a distance C, the roller 221-3 engages the face 230of the cam 228 and is moved about the pivot stud 2II shifting the rodI96-3 longitudinally in the brackets I91 and I98 to substantially thebroken line position 254 (Fig. 10). This movement of the rod I96-3rotates the ring member I19 to release the index pawl I60, as previouslydescribed, and to rotate the indexing wheel 153 in a clockwise directionas viewed in Fig. 10, thus rotating the spindle I02 and drum IIO toadvance a successive portion of unground blade blank intooperativeposition with respect to the grinding wheel 5.

Upon reaching its limit of movement to the left, as controlled by thefinger 36 of the dog 19, the carriage I is reversed and moved to theright to carry the next portion of the blade I24 across a portion of theperipheral abrading face of the grinding wheel 5. During each workstroke of the carriage and blade holding fixture, the indexing pawl I60engages the indexing wheel 153 to secure the blade holding drum againstrotation during the grinding operation. The drawing of the blade acrossa portion of the peripheral abrading face of the grinding wheel, tendsto rotate the blade holding drum I I0 of the blade holding fixture 3 ina counter-clockwise direction, as viewed in Fig. 10. In order to moreeffectively resist this torque the indexing pawl I60 is arranged so thatthe radial faces I51 of the teeth I56 on the index wheel I53 are engagedby the radial face I62 on the indexing pawl I60. Similarly, the teethI56 and indexing pawl I60 of the blade holding fixture 4 are arranged sothat the radial face I62 on the nose of the pawl resists the rotation ofthe bladeholding fixture spindleinduced during the grinding operation(see Fig. 16). As shown in Fig. 10, the blade holding drum IIO of theblade holding fixture 4 tends to roll in a clockwise direction duringthe grinding operation. i

The reciprocation of the carriage I, with the blade holding fixture atthe grinding station, continues under the control of the dogs I8 and I9,a scallop being ground on each movement to the right and the. spindlebeing rotated or ratcheted at each movement of the fixture to the left,until the tooth blank I90 is rotated into a position in underlyingrelation with respect to the ratcheting pawl I84 to prevent the latterfrom engaging succeeding teeth of the indexing wheel (see Fig. 14). Inthis manner further rotation of the spindle I02 and blade holding head His arrested after the grinding of a predetermined number of scallops onthe blade I24. In

8 setting up the machine the disk ISI for the tooth blank I90 isadjusted by means of the set screw I92 so as to engageand deflect thepawl I84 when the desired number of scallops have been ground on theblade.

While a blade blank is being ground on the blade holding fixture 3 theblade holding fixture 4 is disposed at a distance from the grindingstation, as shown in Fig. 1, and the operator attaches a blade blankthereto and positions the head IIO with the gauge mark 260 set to grindthe first scallop when the blade holding fixture 4 is advanced to thegrinding station. In the eventthat the grinding of the last scallop iscompleted on the blade carried by the fixture 3 before the operator isready to shift the carriage, the tooth blank I90 prevents furtherrotation of the spindle I02 by the pawl I84 and prevents the grinding ofadditional scallops on the blade blanks.

When the operator is ready, the arm 48 on the dog I9 is moved so thatthe finger 36 misses the stop 34 and the blade holding fixture 3 movesaway from the grinding station. As soon as the rod BI is depressed bythe rapid traverse cam 54, the bypass valve 50 is opened to supplyadditional high pressure fluid to the hydraulic cylinder I4 and move thecarriage to bring the blade holding fixture 4 to the grinding station ata relatively high rate of speed. Before the blade I24 on the drum of thefixture 4 engages the abrading surface of the grinding wheel, the

rod 5| is released by the rapid traveling cam 54 to .close the bypassvalve 50 so that the carriage I slows down to normal speed for grindingthe first scallop.

iii

grinding station on the blade holding fixtur and reciprocated across theperipheral abrading surface of the grinding wheel, the scallops are completed and the blade, when removed from the drum H0 and allowed toassume its normal straight line position, appears as indicated in Figs.5 and 6. As shown in these figures, arcuate beveled edges 283 areformedzalong the cutting edge of the blade on the opposite side thereoffrom the edges 26L The juncture of the beveled edges 26I and 263 forms aseries or succession of scalloped or curved cutting edges 284 which aresubstantially continuous along the cutting edge of the blade and rise atsubstantially uniformintervals to a series of peaks or points 265 whichare disposed in a substantially straight line.

The blade holding fixtures 3 and 4 are alternately advanced to thecutting station adjacent the grinding wheel and reciprocated acrossdifferent portions of the crowned face of the latter and then moved awayfrom the grinding wheel so that the operator. can remove the groundblade from the blade holding drum and either reverse theblade forgrinding the,opposite side thereof or, in the event the blade has beenground on both sides, to replace it with a fresh unground blade blank.The grinding wheel is in substantially continuous useful operation,

since, while one blade fixture is being reloaded,

the other blade holding fixture is being reciprocated across thegrinding wheel at the grinding station. Accordingly, by the intermittentand alternate use of a plurality of blade holding fixtures theproduction'of a singlegrinding wheel can be materially increased.

The carriage movement is limited by a suitable adjustmentof the dogs I8and 20" so that on each grinding or work stroke the bowed parts of theblades carried by the fixtures 3 and 4 which contact the grinding wheelare carried completely past the center 2' of the peripheral abradingsurface of the rotating grinding wheel but not beyond the side of thegrinding wheel. Preferably, the dogs are located so that the movement ofthe carriage is' arrested when the centers of the fixtures move beyondthe center 2' lops or serrations being ground. .Thus, the por- While theblade blank carried by the fixture 4 is being ground at the grindingstation, the operator removes the blade, which has just been ground,from the drum of the blade holding fixture 3. This blade, which has hadone operation performed thereon at the grinding station, has anappearance resembling that illustrated in Figs. 3 and 4 upon beingpermitted to resume its normal straight line shape. At each pass of theblade across the face of the grinding wheel, an arcuate tapered edge 2Blis formed. Along the top edge I26 of the blade are formed a series ofspaced lands 262 which separate the scallops from one another. Theoperator then reverses the blade and secures it on the drum IIII so thathis bowed :or bent in the opposite direction from that of the firstgrinding operation. After the reversed blade blank has been advanced tothe tion of the blade blank on the fixture3 in which a scallop is groundis carried completely past the center 2' of the crowned abrading surfaceof the wheel and contacts a portion F of suchabrading surface:Similarly, a blade mounted on the fixture 4 contacts a portion G of theabrading surface of the wheel. The portions F and G are each narrowerthan the grinding wheel 5, so that neither the blades carried by thefixture 3 nor the blades carried by the fixture 4 contact the wholeperipheral abrading surface of the wheel.

At the center of the wheel periphery is a portion H of the grindingsurface which is common to both the portions F and G. This operation ofthe apparatus has an advantageous effect in dressing the grinding wheel.so that the latter remains true and uniform and continuously formsscallops of high accuracy.

In Fig. 20 is diagrammatically illustrated the relationship between theblades and the peripheral abrading surface of the grinding wheel duringthe grinding operation. As a blade I24-3, carried by the fixture 3,approaches the rotating grinding wheel in the direction of arrow 261,initial contact occurs at a corner 26E of the grinding wheel and theheaviest cut takes place at this point. As the movement of the bladeholding fixture carries the portion of the blade being ground toward andbeyond the center 21| of the grinding wheel over the portion F of theabrading surface, the grinding continues. While the blade I is againstthe portion H of the grinding wheel, the abrading action is relativelylight and in the nature of a dressing operation to remove burrs and tofinish the beveled edge surface 26f or 263 as the case may be. Duringthe movement of the blade holding fixture over the return or ratchetingstroke, the taper or dress of the abrading surface of the grinding wheeleffects a row 268, initially engages a corner 269 of the grinding wheel5 where the cutting is started. As the blade l24-4 moves toward andbeyond the center 2' of the grinding wheel over the portion G thereof,the grinding action continues, and in the portion H of the grindingwheel surfacethe dressing and finishing action occurs.

It; is important that during the grinding 'opere atioh the portion ofthe blade blank in contact with the wheel 5 be carried beyond the centeror crown of the latter so as to form scallops or serrations of uniformcharacter. grinding or work stroke the centerline of the spindle I02must move past the center 21! of the abrading surface of the wheel.

The effect of alternately grinding different blades by moving the latteracross the peripheral abrading surface of the grinding wheel fromopposite sides of the wheel is to wear the peripheral surface of thegrinding wheel to a curved shape such as that which is illustrated insomewhat exaggerated form in Fig. 20. During the operation; of theapparatus substantiall the same number of blades are ground on thefixture 3 as on the fixture 4 so that the portions F and G are subjectedto substantially the same abrading action or Wear and the entire crownedperipheral abrading surface of the grinding wheel 5 remainssubstantially unchanged over a long period of operation except fordecrease in diameter. Because of the portion H of the peripheralgrinding surface of the wheel 5 being common to both portions F and G,the latter portions blending smoothly into one another and after aperiod of operation the wear on all portions of the peripheral abradingsurface is substantially uniform. Thus, while the mostintensive grindingmay occur at the corners 266 and 269 when the grinding wheel is new andsubstantially Straight across its peripheral abrading surface, asindicated by the broken line 210 of Fig. 20, the corners, after a periodof operation. become worn away as shown, so that the grinding action maybe more uniform over all portions of the abrading surface traversed byeach blade. except at the center of the wheel where the portion H of theabrading surface is contacted by blades or both fixtures Hence, on eachI holding fixtures so that while a blade is being ground in one fixtureanother blade can be removed from another fixture and replaced by afresh unground blade blank.

What I claim is:

1. In a machine for grinding serrations in the cutting edges ofelongated thin flexible blades, a grinding wheel having a peripheralabrading surface, means for rotating the wheel, a movable table inproximity to the wheel, a plurality of blade carrying fixtures mountedon the table for movement therewith. each fixture including a member forholding a blade during the grinding thereof, and means for moving thetable to bring the several fixtures successively to a grinding stationadjacent the abrading surface of the wheel. said moving means includingmeans for reciprocating each blade holding member to repeatedly draw theblade held thereby across the abrading surface of the wheel while suchmember is at the grinding station.

2. In a machine for grinding serrations in the cutting edges ofelongated thin flexible blades, a grinding wheel having a peripheralabrading surface, means for rotating the wheel, a movable table inproximity to the wheel, a plurality of blade carrying fixtures mountedon the table for movement therewith, each fixture including a member forholding a blade during the grinding thereof, means for moving the tableto bring the several fixtures successively to a grinding stationadjacent the abrading surface of the wheel, means for reciprocating eachblade holding member across the abrading surface of the wheel while suchmember is at the grinding station. and

means for intermittently moving said member in synchronization with thereciprocation thereof to successivelymresent different portions of theblade held thereby to the abrading surface.

3. In a machine for grinding serrations in the cutting edges ofelongated thin flexible blades, a grinding wheel having a peripheralabrading surface, means for rotating the wheel, a movable table inproximity to the wheel, a plurality of blade carrying fixtures mountedon the table for movement therewith, each fixture including a member forholding a blade during the grinding thereof, and means for moving thetable to bring the several fixtures successively to a grinding stationadjacent the abrading surface of the wheel, said moving means includingmeans for prisin a member having an abutment for the support of a bladein arcuate position, a ratchet member connected to the blade supportingmemher, a pawl engageable with the ratchet member to advance the latterand thereby shift the blade supporting member to present a succeedingportion of a blade supported thereby to the abrader, means for actuatingthe pawl, and means for preventing advancement of the ratchet by thepawl after a predetermined number of shifting movements of the bladesupporting member.

5. In a machine for grinding serrations in the cutting edge of anelongated thin flexible blade, an abrader, means for actuating theabrader, and a mechanism for holding a blade and presenting successiveportions thereof to the abrader comprising a member having an abutmentfor the support of a blade in arcuate position, a ratchet memberconnected to the blade supporting member, a pawl engageable with theratchet member to advance the latter and thereby shift the bladesupporting member to present a succeeding portion of a blade supportedthereby to the abrader, means for actuating the pawl, a locking elementarranged to engage the ratchet during each presentment of a bladeportion to the abrader to prevent shifting of the blade supportingmember during such presentment,-and means for preventing advancement ofthe ratchet by the pawl after a predetermined number of shiftingmovements of the blade supporting member.

6. In a machine for grinding serrations in the cutting edge of anelongated thin flexible blade, an abrader, means for actuating theabrader, and a mechanism for holding a blade and presenting successiveportions thereof to the abrader comprising a member having an abutmentfor the support of a blade in arcuate position, a ratchet memberconnected to the blade supporting member, a pawl engageable with theratchet member to advance the latter and thereby shift the bladesupporting member to present a succeeding portion of a blade supportedthereby to the abrader, means for actuating the pawl, a locking elementarranged to engage the ratchet during each presentment of a bladeportion to the abrader to prevent shifting of the blade supportingmember during such presentment, means for withdrawing the element fromlocking engagement with the ratchet after the grinding of each serrationto permit advancement of the ratchet by the pawl, and means forpreventing advancement of the ratchet by the pawl after a predeterminednumber of shifting movements of the blade supporting member.

7. In a machine for grinding serrations in the I cutting edge of anelongated thin flexible blade, an abrader, means for actuating theabrader, and a mechanism for holding a blade and presenting successiveportions thereof to the abrader comprising a member having an abutmentfor the support of a blade in arcuate position, a ratchet memberconnected to the blade supporting member, a pawl engageable with theratchet member to advance the latter and thereby shift the bladesupporting member to present a succeeding portion of a blade supportedthereby to the abrader, means for actuatingthe pawl. a locking elementarranged to engage the ratchet during each presentment of a bladeportion to the abrader to prevent shifting of the blade supportingmember during such presentment, and means for withdrawing the elementfrom looking engagement with the ratchet after the grinding ofeachserration to permit advancement of the ratchet by the pawl.

8. In a blade grinding machine, an abrader, a

mechanism for carrying a blade during the grinding thereof comprising asupport, a member having an arcuate abutment to engage a bent blade,spindle means mounting the member on the support for rotatable movementwith respect thereto, means supplying a grinding liquid to the abraderand a blade carried by the member, and a trough carried by the supportto receive and divert grinding liquid flowing over the member, saidtrough having interfitting relation with the member about the spindle toprevent the flow of grinding liquid to the spindle.

9. In a machine for grinding serrations in the cutting edge of anelongated thin flexible blade, a blade supporting member having anabutment engageable with the blade adjacent the edge thereof oppositeand paralleling the cutting edge and a blade backing element engageablewith one side of the blade adjacent the cutting edge, said abutment andelement having contact with only a minor portion of one side of theblade and being arranged so that the major portion of the side of theblade engaged by the backing element is exposed -for contact withcooling liquid.

10. In a machin for grinding serrations in the cutting edges ofelongated thin flexible blades, a grinding wheel having a peripheralabrading surface, means for rotating the wheel, a plurality of bladecarrying fixtures mounted for successive movement to a grinding stationin proximity to the wheel, means for reciprocating one of the fixtureswhile at the grinding station to draw the blade carried thereby across afirst portion only of theabrading surface, and means for reciproeatinganother of the fixtures while at the grinding station to draw the bladecarried thereby across a second portion of the abrading surface.

11. In a machine for grinding serrations in the cutting edges ofelongated thin flexible blades, a grinding wheel having a peripheralabrading surface, means for rotating the wheel, a movable table inproximity to the wheel, a plurality of blade carrying fixtures mountedon the table for movement therewith, each fixture including a member forholding a blade during the grinding thereof, means for moving the tableto bring the several fixtures successively to a grinding stationadjacent the abrading surface of the wheel, said moving means includingmeans for reciprocating each blade holding member at reduced speedacross the abrading surface of the wheel while such member is at thegrinding station, and means for intermittently moving said member insynchronization with the reciprocation thereof to successively presentdifferent portions of the blade held thereby to the abrading surface.

12. In a machine for grinding serrations in the cutting edges of blades,an abrader and actuating means therefore, a. holder to receiv a bladeand support the same during grinding, a ratchet member connected to theholder, a pawl engageable with the member to intermittently advance thelatter and thereby shift the holder to present different portions of asupported blade to the abrader, means for actuating the pawl, and

means interposed between the ratchet and pawl.

after a predetermined number of shifting movements of the holder toprevent further advance m nt of the. ratchet member.

13. A grinder comprising a supporting structure. an abrasive wheel andmeans for rotating the same. a movable carriage, a holder on thecarriage for supporting the work to be ground, means for moving thecarriage to move the holder between a loading station removed from thewheel and a grinding station adjacent the wheel and for reciprocatingthe holder at the grinding station, a ratchet member connected to theholder, a pawl engageable with the ratchet to advance the latter andthereby shift the holder to present different portions of supported workto the Wheel, an abutment on the supporting structure, and mechanism foractuating th pawl in timed relation to the reciprocation of the holder,including a member engageable with the abutment during saidreciprocation at the grinding station, said mechanism also including alost motion connection to permit the last named member to ride over theabutment as the holder moves to the grinding station.

14. A grinder comprising an abrasive wheel, a reciprocable carriage andactuating means therefor, a-pair of spaced work holders mounted on thecarriage for rotativ movement about axes normal to the direction ofcarriage reciprocation and successively movable with the carriage to agrinding station adjacent the wheel, means responsive to the carriagemovement for controlling the actuating means to drive the carriage andreciprocate each holder back and forth over a relatively short pathadjacent the wheel while the holder is at the grinding station, andmeans associated with each holder and responsive to the reciprocationthereof adjacent the wheel to rotate the holder.

15. A grinder comprising a supporting structure, an abrasive wheel, areciprocable carriage and actuating means therefor, a pair of spacedwork holders mounted on the carriage for independent rotative movementabout axes normal to the direction of carriage movement and successivelymovable with the carriage to a grinding station adjacent the wheel,means responsive to the carriage movement for controlling the actuatingmeans to drive the carriage and reciprocate each holder back and forthover a relatively short path at the grinding station, an abutment on thesupporting structure, and separate means associated with each holder andincluding a member engageable with said abutment to rotate the holdersin response to the carriage movement while each holderis adjacent thewheel.

16. In a machine for grinding serrations in th cutting edge of anelongated thin flexible blade, an abrader, a blade holder movablymounted adjacent the abrader, said holder including a member forreceiving a blade to support the same during the grinding thereof, meansfor moving the holder toward and away from the abrader to intermittentlypresent a supported blade to the abrader, means responsive to saidmovement of the holder for shifting the member after each presentment toadvance the blade and present a different portion thereof to the abraderduring the next movement of the holder toward the abrader, and anelement movable after each shifting of the member to lock the same inshifted position during the abrading'of the blade.

17. In a machine for grinding serrations in the cutting edge of anelongated thin flexible blade, 21; blade supporting member having anabutment engageable with th blade along the non-cutting edge thereof anda backing element spaced from the abutment and engageable with the bladeadjacent the cutting edge, and apertures through the backing element toadmit liquid coolant to the space between the abutment and the backingelement during grinding.

18. In a machine for grinding serrations in the cutting edge of anelongated thin flexibleblade,

a blade supporting member having a pair of spaced, substantiallyparallel narrow and. substantially continuous abutments for engaging oneside of a blade to support the same during grinding, said abutmentshaving contact with only a minor portion of one side of the blade andbeing arranged so that the major portion of the side of the bladeengaged thereby is exposed for contact with liquid coolant, and meansfor admitting liquid coolant to the space between the abutments tocontact the portions of the blade exposed therebetween.

19. In a machine for grinding serrations in the cutting edge of anelongated thin flexible blade, a member having spaced abutments tosupport a blade in an upright position, said abutments contacting spacedportions of one side of a supported blade to permit cooling liquid tocontact portions of said side of the blade disposed between theabutments, and the space between abutments being less than the width ofthe blade.

20. In a machine for grinding serrations in the cutting edge of anelongated thin flexible blade, a member having spaced abutments tosupport a blade in an upright position, said abutments contacting spacedportions of one side of a supported blade to permit cooling liquid tocontact portions of said side of the blade disposed between theabutments, the space between'abutments being less than the width of theblade and the top surface of the member adjacent the upper edge of theblade being generally below the level of said edge, and said memberhaving a portion extending upwardly above said level, said upwardlyextending portion approximately paralleling a supported blade to directliquid coolant against said side of the blade between the abutments.

21. In a machine for grinding blades, an abrader and actuating meanstherefor, a fixture mounted for relative reciprocating movement towardand away from the abrader and having a drum for receiving a blade andholding the same in bent position for presentment to the abrader, meansfor reciprocating the fixture, means operative in response to themovement of the fixture for turning the drum to successively presentdifferent portions of a blade to the abrader, means having connectionwith the drum to lock the same against rotation, and means operative inresponse to the movement of the fixture for releasing the locking meansfor rotation of the drum by the turning means.

22. In a machine for grinding blades, a wheel having a peripheralabrading surface, a fixture and means mounting the same forreciprocating movement toward and away from the wheel along a pathparalleling the rotational axis of the wheel, a holder on the fixturefor support ing a blade to be carried thereby-on a work stroke from oneedge of the wheel surface to the center 7 thereof and on a return strokefrom the center past the wheel edge, and means operative in response tothe movement of the fixture for shifting the holder thereon to presentdifferent portions of a blade to said abrading surface on succeedingwork strokes, said shifting means being arranged to commence theshifting of the holder'on each return stroke prior to movement beyondthe wheel edge of the blade portion ground on the preceding work stroke.

23. In a blade grinding machine, a wheel having a peripheral abradingsurface and actuating means therefor, a plurality of .blade carryingfixtures mounted for successive movementto a grinding station inproximity to the wheel,

